This paper attempts to assess the knowledge and attitude on HIV/AIDS among school students of Iran. The following data sources were searched for eligible studies: Medline, Science Direct, CINAHL, Scopus, Web of Science, SID, ISC, Magiran, and Google Scholar from 1990 to the end of 2016. The quality of the studies was evaluated using the 22-item STROBE checklist. The highest level of awareness belonged to sharing clothes (93.15) and blood transfusion, respectively (86.31), while the lowest level of awareness was related to transmitting HIV from mother to child (42.05). The study identified a substantial gap in the knowledge, negative attitude towards HIV/AIDS and its transmission among Iranian school students. Accordingly, schools should be regarded as one of the main focuses of activities in the strategies of AIDS risk reduction, and education of school students about all aspects of HIV/AIDS has to be considered seriously by the education policymakers.